1. Field of the Invention
The present invention relates to a device for collecting solid, liquid, and vapor sample from surfaces.
2. Background Information
One of the most challenging parts of an effective chemical detection system is the means of collecting and delivering sample to the detector. There have been developed a wide variety of chemical detection applications for chemical sample types. These applications range from volatile to solid compounds that may be found in a host of different media ranging from air, to water, to solid surfaces such as soil. The additional requirements of real-time detection and use in mobile applications adds to the challenge. Many detection technologies (e.g., mass spectrometry, ion mobility spectrometry, optical spectroscopy, etc.) have been developed over the years and trace detectors now exist that can detect a wide range of chemicals. Whereas the specificity of a detector is the key to minimizing false positive rates, the sampler is vital for maximizing detection rates, since if a trace sample is not delivered to the detector, it will result in a non-detect event.
An effective sampling system must have the following operational characteristics: (1) access to the surface and volume containing the contamination, (2) removal of the contamination, particularly for liquids and solids that can stick tightly to surfaces, (3) delivery of the material to a trace detector in a step that involves vaporization, and (4) minimizing cycle time and carryover effects. For trace chemical analyzers, the liquid and solid sample must be vaporized. There are a large number of published and patented chemical sampling devices that deal with some part of the applications described above, but none accomplish all of the requirements.
U.S. Pat. No. 4,541,268 issued to Odernheimer discloses a collector surface that is brought into contact with material to be sampled and then transferred to a membrane that is heated for delivery to a detector. The membrane is based on selective permeation and therefore has the function of enriching compounds, but in fact this is achieved through selectivity, which is molecule dependent, and is therefore prone to selectively suppress some compounds. Furthermore, a permeation membrane reduces the response time and recovery of the sampler. Several samplers use membranes as the interface between the sample and the detector including U.S. Pat. No. 5,517,206 issued to Sickenberger, et al. and U.S. Pat. No. 5,843,379 issued to Kristensen.
U.S. Pat. No. 6,817,225 issued to Boyd, et al. disclosed a volatile organic compound (VOC) sampling probe that is partially buried in the ground. U.S. Pat. No. 7,281,439 issued to Albro, et al. also discloses a VOC sampler for subsurface soil analysis. However, neither of these devices allow mobile use, nor do they sample liquid or solid samples effectively. U.S. Pat. No. 7,357,044 issued to Sleeman, et al. discloses a movable sample collection and desorption device, but it does not allow vapor and condensed compound detection, nor does it allow for sampling in dirty environments such as soil.